The present invention relates to a fuel conduction system for conducting fuel between a fuel source and a fuel consuming device which are either integrated as a single unit or apart as separate units. More particularly, the invention relates to a fuel conduction system arranged to prevent siphoning of the fuel in the event of a fuel line failure as well as inhibiting the occurrence of flash-back at the fuel source.
Portable fuel consuming equipment including portable heaters and engine driven generator sets are known equipment which are widely used, for example in the field of construction and the like. In such equipment, fuel is required to be pumped through flexible fuel lines between a fuel source and a pump of the equipment. These lines include a pump supply line and a pump pressure regulation bypass return line which typically run along the floor.
Damage to these lines, for example due to piercing of the line or fire, can result in numerous undesirable situations including siphoning or pumping of the contents of the fuel source onto the floor or flash-back through the lines back to the fuel source. Numerous requirements, both regulatory as well as user or site imposed requirements, are thus commonly required to be met when using portable fuel consuming equipment in order to satisfy either safety concerns, environmental concerns or individual concerns relating to a particular use of the equipment.
Describing the equipment now in further detail, fuel consuming equipment which is intended for temporary use generally incorporates an integral fuel tank which is factory assembled to a platform, frame or body of these devices. The weight of stored fuel however can be quite substantial and added to the weight of the fuel consuming equipment is often a major impediment to portability. Portability is a major attribute of the functionality of such equipment which frequently must be moved and handled involving such operations as loading and unloading from trucks and being moved about on temporary sites often over soft, uneven or obstacled ground.
In the case of lighter equipment such as portable heaters, the moving and handling of the equipment can be much ameliorated if the fuel is supplied from fuel storage containers which are separate from the fuel consuming equipment so that the equipment and fuel storage container can be independently handled on and off the temporary sites. Fuel lines may thus be required to extend between the fuel source and the fuel consuming equipment over a considerable distance over which the fuel lines are susceptible to one of many possible forms of damage possibly resulting in siphoning of the fuel or a flashback situation.
In the case of heavier equipment including diesel driven generator sets and pumps, portability is dealt with by assembly of these devices complete with a separate fuel storage container onto a common platform such as a skid which facilitates movement about on temporary sites. This arrangement similarly requires fuel lines to extend between the fuel source and the fuel consuming equipment with the lines again being susceptible to one of many possible forms of damage possibly resulting in siphoning of the fuel or a flashback situation. The fuel lines in this instance are required to meet any factory built equipment requirements.
The above mentioned approaches to conducting fuel between a fuel storage container and a fuel consuming device however affect concerns with regard to safety and environment and change the category into which the equipment falls with regard to regulatory enforcement that applies.
The options of supplying fuel containers either integrally or remotely with respect to fuel consuming devices and supplying repair and maintenance shop assemblies complete with separate fuel containers into the field causes the equipment to fall, from a regulation standpoint, into the category of a field installation as opposed to factory assembled packaging. Safety requirements that apply to fuel storage and fuel lines with factory assembled equipment, as opposed to field installations, while similar in their general intent to prevent fuel escape, differ significantly in practical details as to how compliance can be achieved.
Furthermore, equipment with either integral or remote fuel containers and maintenance shop assemblies complete with separate fuel containers fall into the subcategory of temporary field installations, including repair and maintenance shop assemblies transported on and off temporary sites, as opposed to permanent field installations. The same environment and safety regulations that apply to permanent use field installations of fuel consuming devices also apply to temporary use field installations. Regulations that apply to stationary, permanent use equipment however, are often not entirely appropriate to the circumstances that apply to portable, temporary use equipment.
It is readily recognisable that such requirements for permanent field installations could impose relatively time consuming and expensive installations in relation to short term equipment requirements. Furthermore the installations which meet permanent use requirements interfere with operational flexibility on temporary sites and may be sensitive to temporary use conditions such as exposure to extreme temperatures, weather conditions and handling problems due to freighting from site to site.
It is a broad requirement of all of the various sets of regulations that a fuel system not permit fuel in storage containers to escape should a fuel line failure occur. Enforcement with respect to factory assembled packages has always been strict through equipment certification procedures but enforcement in temporary situations until recently has been tenuous. Recent concerns about environmental issues have brought about tighter enforcement.
In addition to requirements regarding siphoning, due to the possibility of flash-back, a further requirement which can apply to particular applications of fuel consuming equipment is the incorporation of a flash-back arrestor. In the event of a fuel line burn through, for example due to a floor fire, combustion in the form of a flash-back has the potential to spread through fuel residue and vapour remaining in the supply line to the fuel source unless a flash-back arrestor is in place. Portable fuel consuming equipment having supply and return lines extending between a pump and a fuel source can thus be easily susceptible to flashback arising from floor fires and the like when no arrestor is provided.
An example of portable fuel consuming equipment is illustrated in U.S. Pat. No. 3,630,225 to Chitel. A portable heating system is described which makes use of a remote fuel tank by extending a supply line and a return line between the fuel tank and a pump mounted integrally on a heater unit in a common configuration. An anti-siphon valve is mounted on the supply line adjacent the fuel tank to prevent siphoning of the contents of the fuel tank through the supply line in the event of a line failure. The arrangement of Chitel however, similarly to conventional configurations commonly employed, does not meet basic requirements imposed on such equipment due to an exposed return line which could either partially siphon the contents of the fuel tank therethrough in the event of a line failure, or could result in fuel being pumped through the return line onto the floor if only the return line were damaged. Furthermore, Chitel provides no protection against possible flash-back.
According to one aspect of the present invention there is provided a fuel conduction system for conducting fuel between a fuel source and a pump having an inlet, a main outlet and a pressure regulation return outlet, the fuel conduction system comprising:
a supply line extending in a longitudinal direction from a pump connecting end arranged to be connected to the inlet of the pump to a source connecting end arranged to be connected to the fuel source; and
a return line extending substantially concentrically through the supply line in the longitudinal direction of the supply line from a pump connecting end adjacent the pump connecting end of the supply line and arranged to be connected to the pressure regulation return outlet to a source connecting end adjacent the source connecting end of the supply line arranged to be connected to the fuel source.
With the return line arranged to extend concentrically through the supply line, the only manner in which the return line can leak fuel into the surrounding environment is if the supply line surrounding the return line is also pierced, thus effectively cutting off the supply of fuel to the pump to prevent fuel from being continuously pumped out during a line failure. The use of the fuel conduction system as described above thus permits requirements to be met regardless of whether the fuel source is mounted integrally or apart from the fuel consuming device.
An automatic shut-off valve is preferably coupled in series with the supply line adjacent the source connecting end which includes a valve member biased towards a closed position. The valve member is arranged to be opened in response to a reduction in pressure in the supply line associated with activation of the pump. The incorporation of a valve in the supply line further ensures that fuel is not spilled from the fuel storage container by siphoning through the supply line. The valve also effectively acts as a flashback arrestor for meeting both safety and environmental requirements, regulatory or otherwise, relating to both flashback and siphoning in a fuel conduction system.
The valve may be arranged to extend upwardly from an inlet to an outlet with the valve member being weighted so as to be seated on the inlet in the closed position in response to a reduction in pressure in the supply line associated with siphoning action of the supply line while being arranged to be raised upwardly from the inlet in an open position in response to a reduction in pressure in the supply line associated with activation of the pump.
A tank fitting may be provided which is arranged to selectively mount the source connecting ends of the respective supply and return lines to the fuel storage container. The tank fitting would preferably include the valve mounted integrally thereon.
There may be provided a flashback arrestor coupled in series with the return line adjacent the source connecting end thereof in addition to the valve on the supply line. The fuel conduction system is thus arranged to meet requirements regarding flashback protection.
In addition to the valve on the supply line, there may also be provided a vent coupled to the return line adjacent the source connecting end thereof. The vent would be arranged to permit air to be drawn into the return line so as to prevent siphoning of fuel from the fuel source through the return line in the event of line failure. The vent preferably comprises an air flow check valve being arranged to restrict passage of fuel from the return line through the check valve while permitting air to be drawn into the return line.
An outlet line is preferably arranged to be coupled between the main outlet of the pump and a fuel consuming device with an envelope being provided surrounding the outlet line between respective ends thereof. The envelope is preferably coupled in communication with the supply line so as to produce a reduction in pressure within the envelope surrounding the outlet line upon activation of the pump. The envelope and the outlet line may comprise respective elongate tube members with the outlet line extending substantially concentrically through the envelope.
A manual shut-off valve may be coupled in series with the supply line adjacent the source connecting end thereof.
For connection of the lines to the pump, a pump connector may be coupled to the respective pump connecting ends of the supply and return lines. The pump connector preferably includes a pump inlet line in communication with the pump connecting end of the supply line which is arranged to be selectively coupled to the inlet of the pump and a pump return outlet line in communication with the pump connecting end of the return line which is arranged to be selectively coupled to the pressure regulation return outlet of the pump.
For connection of the lines to the fuel source, a fuel source connector may be coupled to the respective source connecting ends of the supply and return lines. The fuel source connector preferably includes source outlet line in communication with the source connecting end of the supply line which is arranged to be selectively coupled to the fuel source and a source inlet line in communication with the source connecting end of the return line which is arranged to be selectively coupled to the fuel source.
According to a second aspect of the present invention there is provided a fuel conduction system in combination with a fuel consuming device, the system comprising;
a fuel source;
a pump having an inlet, a main outlet and a pressure regulation return outlet;
a supply line extending in a longitudinal direction from a source connecting end coupled to the fuel source to a pump connecting end coupled to the inlet of the pump;
a return line extending substantially concentrically through the supply line in the longitudinal direction of the supply line from a source connecting end coupled to the fuel source to a pump connecting end coupled to the pressure regulation return outlet of the pump; and
an outlet line coupled between the main outlet of the pump and the fuel consuming device.
Whether the fuel source and the fuel consuming device are deployed integrated as a single unit or apart as separate units, when connected utilizing the fuel conduction system, the combination will prevent fuel leakage arising from fuel being pumped out due to a return line failure.
To further protect the fuel source from either draining, siphoning or pumping there may be provided an automatic shut-off valve coupled in series with the supply line adjacent the source connecting end including a valve member which is biased towards a closed position. The valve member is preferably arranged to be opened in response to a reduction in pressure in the supply line associated with activation of the pump.
As noted above, the incorporation of a valve in the supply line further ensures that fuel is not spilled from the fuel storage container by siphoning through the supply line as well as effectively acting as a flashback arrestor. Safety and environment concerns as they apply to both field installation and the factory assembly of fuel storage and fuel consuming equipment may thus be satisfied.
Preferably the supply and return lines are selectively separable from both the fuel source and the pump so as to permit the fuel source to be readily disconnected from and connected to the pump.
There may be provided an envelope surrounding the outlet line between respective ends thereof. The envelope is preferably coupled in communication with the pump inlet so as to produce a reduction in pressure within the envelope surrounding the outlet line upon activation of the pump.
The fuel source preferably comprises a portable fuel container which is supported for rolling movement across the ground. The fuel consuming device may be arranged to be selectively supported on the fuel source so as to permit selective separation thereof. The pump may be mounted integrally on either the fuel consuming device or the fuel source in this instance.
According to a further aspect of the present invention there is provided a portable fuel source for supplying fuel to a fuel consuming device having a pump including an inlet, a main outlet and a pressure regulation return outlet, the portable fuel source comprising:
a fuel storage container supported for rolling movement across the ground;
a supply line arranged to be coupled between the container and the inlet of the pump;
a return line arranged to be coupled between the container and the pressure regulation return outlet of the pump; and
a valve mounted integrally on the container and being arranged to be coupled in series with the supply line, the valve including a valve member which is biased towards a closed position, the valve member being arranged to be opened in response to a reduction in pressure in the supply line associated with activation of the pump.
The return line extends substantially concentrically through the supply line between respective ends of the lines for additional protection fuel spillage from the container. A vent on the return line arranged to permit air to be drawn into the return line inhibits siphoning of fuel from the fuel source through the return line for protection against siphoning of the fuel container contents in additional to the valve on the supply line.
A flashback arrestor mounted integrally on the container and being arranged to be coupled in series with the return line in addition to the valve on the supply line ensures that the container is adequately protected against flashback.